This invention relates to a fire detector for use in a fire alarm system in which a temperature increase due to a fire is sensed by a temperature sensor such as a thermistor or a platinum wire.
There have conventionally been manufactured fire detectors of the type in which a temperature sensor, such as a thermistor or a platinum wire, senses a temperature increase due to a fire to detect the occurrence of the fire. In such fire sensors, the portion of the temperature sensor which is exposed to the ambient atmosphere is enclosed in a metal tube or a resin tube in order to protect the temperature sensor from an exterior shock.
When a temperature sensor is enclosed in a metal tube or a resin tube as described above, the thermal capacity becomes greater, and its response ability is lowered. Therefore, to enhance its response ability, the temperature sensor has to be exposed to the ambient atmosphere. However, in this case the temperature sensor can not be protected against impacts, etc., applied thereto from the exterior. Also, there is no means for achieving shielding from external electrical noises developing when the temperature sensor is enclosed in a metal tube.